1. Technical Field
The present invention relates to a display device, and particularly to a technology for a display device that projects a virtual image display.
2. Related Art
There have been proposed head-up displays that directly project a display in the field of view of a user. A known example of such a head-up display is an in-vehicle display device that projects a display of an indicator or the like in the field of view of the driver. By projecting a display in the field of view of the driver, the amount of sightline movement of during driving can be reduced. Further, by setting the position where the display is focused to be distant from the driver, it is possible to reduce the difference between the position of an object viewed through the windshield and the position where the virtual image is focused, allowing the display to be more easily viewed. Moreover, by changing the position where the virtual image is focused, the image can be displayed as if it moves as the vehicle travels. For example, JP-A-6-43392 proposes a technology for changing the position where the virtual image is focused. In the technology proposed in JP-A-6-43392, movement of the modulation unit of a CRT or a lens that is part of the projection optical system is used to change the position where the virtual image is focused.